You can lodge a complaint through TIO. I have done this (on recommendation of another person in the forum) and while it's onerous (no doubt intentionally) it does mean someone in Optus has to be assigned to your case.
If each person having problems takes action - and it seems to be a lot of people - Optus may take note.
@LindaLee99, we can always go in and take a look.
We've had a few reports from customers on social media and the forum. We've raised the issue with the online complaints form and are waiting on a resolution.
Regarding your enquiry, I understand what you're saying but the charge is mentioned in the CIS of the contract you've received.
It's not something that we make secret.
We do assess these sorts of things on a case by case basis. Send us a private message, I'll see what I can do for you.
I'm of the opinion the Optus Late Fee is not unreasonable. First up if you owe less than $50 it doesn't apply. Secondly applying variable interest rates on variable plans is quite complex and doesn't necessarily represent the costs incurred by Optus when you don't pay on time. The $15 fee is also a one off and is not re-applied the following month.
There are of course many other approaches (although I don't think any major institution only charges a percentage interest penalty) but Optus is up front with a simple format.
TIO is generally only useful when Optus has broken their contractual obligations (or there's a dispute). In this case the late fee is a long standing contractual element and IMO TIO are unlikely to be able to do much.
But as you say, including the TIO might make Optus more inclined to help out.
That said, Optus (like most large institutions) are generally pretty good at reversing a one off fee due to what ever reason, so long as it is a one off)